<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title></title>
		<style>
			div{
				width: 300px;
				height: 300px;
				/*background-color: deepskyblue;*/
				/*边框 border:边框的宽度 | 边框样式| 边框颜色*/
				border:2px solid red;/*单实线*/
				border:2px dashed red;/*虚线*/
				border:2px dotted red;/*点线*/
				border-top:2px solid red;
				border-right-color: green;
				border-right-style: dashed;
				/*内边距：内容和边框的距离*/
				padding: 10px;
				padding: 10px 20px;
				padding: 10px 20px 30px;
				padding: 10px 20px 30px 40px;
				/*外边距；盒子和盒子之间的距离*/
				margin: 10px;
				margin: 10px 20px;
				margin: 10px 20px 30px;
				margin: 10px 20px 30px 40px;
				/*水平居中：左右的外边距要自动*/
				/*margin: auto;
				margin: 0 auto;*/
			}
			
			
		</style>
	</head>
	<body>
		<div><div>div内容</div></div>
		
	</body>
</html>
